Certain known electronic locks employ coding techniques such as number scramblers or encoders that manipulate a manually selected key combination to provide, on a magnetic card or punched card or the like, an encoded key combination in scrambled order. In locks of this type, a card-reading mechanism is usually required and the security against detection of the key combination is usually preserved only to the extent of the complexity of the scrambling technique. It would be desirable in electronic locks to obviate the dependence for security upon the complexity of the scrambling or encoding of key combinations and still retain the versatility and multiplicity of possible individual combinations which can be set conveniently in the field.